Finite Element Analysis Of Flexible Roll-die Forming Process

Flexible roll-die forming is a new kind of plastic forming technology. it is processed by the method that sheet pressed by the mould while rolls feeding. Flexible roll-die forming technology adapts to the concept of energy-saving and emission reduction while conforming to the requirements in the automotive lightweighting, its product is widely used in automotive and aerospace fields. The flexible roll-die forming process is a very complicated highly nonlinear deformation process. But theory of flexible roll-die forming technology is not perfect, and we are unable to judge whether the structure design and the technology is reasonable. This paper done numerical simulation by using the finite element method to research the deformation mechanism about the forming process.The paper analysed the elastic-plastic constitutive relation in the flexible roll-die forming process, including Hooke’s law, Yield criterion and hardening rule of elastic material stage. The paper also researched the selection of stress and strain under the condition of large deformation and geometric nonlinearity, used penalty function algorithm in the contact analysis, then obtained corresponding nonlinear finite element balance equation and finished theoretical description of the model. The flexible roll-die forming process is a quasi-static process, according to integral method of central difference method, then solved finite element equations of the system through recursive format.The basic mechanical properties of TRIP590and DP980high-strength steel were obtained by uniaxial tensile test. Obtained the relationship between true stress and plastic strain of the material, and got relevant parameters of anisotropy Hill48yield criterion about DP980. They can became material properties for finite element model. Created high-quality finite element model of flexible roll-die forming for automotive B pillar reinforcement plate based on broad-scale finite element software Hypermesh and ABAQUS/CAE.Made the total procedure finite element simulation of the flexible roll-die forming process with ABAQUS/Explicit solver based on display dynamic algorithm. The equivalent stress, equivalent plastic strain and section thickness were obtained, the forming mechanism of DP980sheet was mastered, roll forming force law was obtained, and section springback of plate was forecasted. Contrasted the difference between Mises yield criterion model and Hill48yield criterion model to obtain how yield criterion had an influence on the deformation results. Researched on the law in different pass space of the plate forming. Contrasted the difference between DP980model and TRIP590model to obtain how strength of the material had an influence on the forming effect, forming force and section springback. Forming test of B-pillar reinforcement plate was done with the flexible roll-die forming machine that was developed by the our research group, and effectiveness of finite element analysis about flexible roll-die forming process was obtained experimental verification with the formed part.